Originally Posted by pfdaxe

Could be the temps. I have a supercharged Toyota 4Runner with all of the fuel mods, and it throws a codes and runs a bit sluggish in the summer. It runs strong in the cooler months. On the Z, I have a Nismo exhaust with Top Speed axle back and haven't had any codes.

I will say, adding the oil cooler really helped my oil temp. Last summer when I bought the car, it was around 230 degrees. This year in 110+ temps I'm running about 200-210.